SDK12.1 NRF51822SDK12.1 NRF51822

Question

static uint32_t dfu_char_add(ble_dfu_t * p_dfu, const ble_dfu_init_t * p_dfu_init)
{
 /**@snippet [Adding proprietary characteristic to S110 SoftDevice] */
 ble_gatts_char_md_t char_md;
 ble_gatts_attr_md_t cccd_md;
 ble_gatts_attr_t attr_char_value;
 ble_uuid_t ble_uuid;
 ble_gatts_attr_md_t attr_md;

 memset(&cccd_md, 0, sizeof(cccd_md));

 BLE_GAP_CONN_SEC_MODE_SET_OPEN(&cccd_md.read_perm);
 BLE_GAP_CONN_SEC_MODE_SET_OPEN(&cccd_md.write_perm);

 cccd_md.vloc = BLE_GATTS_VLOC_STACK;

 memset(&char_md, 0, sizeof(char_md));

 char_md.char_props.notify = 1;
 char_md.char_props.write = 1; //dfu chenyaojie 
 char_md.char_props.read = 1;
 char_md.p_char_user_desc = NULL;
 char_md.p_char_pf = NULL;
 char_md.p_user_desc_md = NULL;
 char_md.p_cccd_md = &cccd_md;
 char_md.p_sccd_md = NULL;

 ble_uuid.type = p_dfu->uuid_type;
 ble_uuid.uuid = 0x0001;

 memset(&attr_md, 0, sizeof(attr_md));

 BLE_GAP_CONN_SEC_MODE_SET_OPEN(&attr_md.read_perm);
 BLE_GAP_CONN_SEC_MODE_SET_OPEN(&attr_md.write_perm);

 attr_md.vloc = BLE_GATTS_VLOC_STACK;
 attr_md.rd_auth = 0;
 attr_md.wr_auth = 1;
 attr_md.vlen = 1;

 memset(&attr_char_value, 0, sizeof(attr_char_value));

 attr_char_value.p_uuid = &ble_uuid;
 attr_char_value.p_attr_md = &attr_md;
 attr_char_value.init_len = 0;
 attr_char_value.init_offs = 0;
 attr_char_value.max_len = BLE_L2CAP_MTU_DEF;

 return sd_ble_gatts_characteristic_add(p_dfu->service_handle,
 &char_md,
 &attr_char_value,
 &p_dfu->control_point_char);
 /**@snippet [Adding proprietary characteristic to S110 SoftDevice] */
}



uint32_t ble_dfu_init(ble_dfu_t * p_dfu, const ble_dfu_init_t * p_dfu_init)
{
 uint32_t err_code;
 ble_uuid_t ble_uuid;
 ble_uuid128_t nus_base_uuid = BLE_DFU_BASE_UUID;

 VERIFY_PARAM_NOT_NULL(p_dfu);
 VERIFY_PARAM_NOT_NULL(p_dfu_init);

 p_m_dfu = p_dfu; // TODO: find a nicer solution to this

 // Initialize the service structure.
 p_dfu->conn_handle = BLE_CONN_HANDLE_INVALID;
 p_dfu->evt_handler = p_dfu_init->evt_handler;
 p_dfu->is_waiting_for_disconnection = false;
 p_dfu->is_ctrlpt_notification_enabled = false;

 /**@snippet [Adding proprietary Service to S110 SoftDevice] */
 // Add a custom base UUID.
 err_code = sd_ble_uuid_vs_add(&nus_base_uuid, &p_dfu->uuid_type);
 VERIFY_SUCCESS(err_code);

 ble_uuid.type = p_dfu->uuid_type;
 ble_uuid.uuid = BLE_UUID_DFU_SERVICE;

 // Add the service.
 err_code = sd_ble_gatts_service_add(BLE_GATTS_SRVC_TYPE_PRIMARY,
 &ble_uuid,
 &p_dfu->service_handle);
 /**@snippet [Adding proprietary Service to S110 SoftDevice] */
 VERIFY_SUCCESS(err_code);

 // Add the RX Characteristic.
 err_code = dfu_char_add(p_dfu, p_dfu_init);
 VERIFY_SUCCESS(err_code);

// err_code = ble_dfu_buttonless_char_add(p_dfu);
// VERIFY_SUCCESS(err_code);
 
 err_code = nrf_dfu_flash_init(true);
 VERIFY_SUCCESS(err_code);

 nrf_dfu_settings_init();

 return NRF_SUCCESS;
}
 
 this is my code on DFU function, I copy to the example of experimental_ble_app_buttonless_dfu on SDK12.1. I used nrfgo studio to program s130_nrf51_2.0.1_softdevice , boot_setting.hex(used nrfutil to produce ), nrf51822_xxac_s130. and then my cellphone can connect to "DFUTarg" to DFU my application. I can used to cellphone to connect my application finally.

I click to "1" and "2" in the picture,but it can not skip to boot mode(DFUTarg).this is why i do not know. 
 
 If i direct to "DFU" download to application,then the cellphone stop at the following screen.

why i can not skip to the boot mode from the application?